The present disclosure relates, in general, to electronics, and more particularly, to circuits and method for providing power to electronic devices. Various methods and structures may be used in switching power supply controllers, such as pulse width modulated (PWM) controllers or pulse frequency modulation (PFM) controllers. The switching power supply controllers function to regulate an output voltage to a desired value.
Fixed frequency controllers, such as fixed-frequency PWM controllers, may not respond quickly to load transients. For example, a fixed-frequency PWM controller may not provide a consistent response to a rapid step change in the load. Also, fixed-frequency PWM controllers may have beat frequencies that resulted in noise in the output voltage.
A Ramp Pulse Modulation (RPM) based controller is a type of PWM controller that can provide improved transient response by determining a duration of phase pulses using an average current of the output voltage.
In some RPM based controllers, an error signal used in the regulation of the output voltage requires a wide operational range when a target voltage value of the output voltage is variable, which increases the difficulty and complexity of the design. Furthermore, RPM based controllers may require external compensation (that is, a compensation circuit outside of the integrated circuit that includes the controller) of the error amplifier used to produce the error signal in order to meet tight regulation requirements under various transient conditions, which may increase a parts count, a size, and a cost of the power converter and increase a pin count of the integrated circuit that contains the error amplifier. Finally, a multi-phase RPM controllers may not be scalable, that is, it may be difficult or impossible to increase the number of phases used past a fixed limit.
Those skilled in the field of the present disclosure will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of the embodiments.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments. This avoids obscuring the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the disclosures herein. The details of well-known elements, structures, or processes that are necessary to practice the embodiments and that are well known to those of skill in the art may not be shown and should be assumed present unless otherwise indicated.